Method of producing cutbacks



Oct. 27, 1936. T. ROBINSON METHOD OF PRODUCING CUTBACKS Filed Oct. 12, 1953 2 Sheets-Sheet 1 m ///Y/ 9 442 x M g \fl/M F v? m x\ :w A 5 J x 1 I 1 T d n f .1... 7 M f M w a m n In" //V E LE wfi mg? mg 1 /VV 7/ E INVENTOR 44am BY M Mr- MM ATTORNEYS Oct. 27, 1936. T. ROBINSON 2,058,913

METHOD OF PRODUCING CUTBACKS Filed 001;. 12, 1953 2 Sheets-Sheet 2 Fig.3-

ATTO RN EYS understood that the utility Patented Oct. 27, 1936 UNITED STATES PATENT OFFICE Lancaster Processes, Inc., Long Island City,

- N. Y., a corporation of New York Application October 12, 1933, Serial No. 693,391

8 Claims.

This invention relates to'cutbacks produced by treating relatively heavy viscous substances with a solvent or iiuxand is concerned more particularly with a novel method by which such materials can be made rapidly and at low cost. The method of the invention may be used to special advantage in the production of cutbacks of asphalt and coal tar pitch, and, therefore, for purposes of explanation, the details of the new method will be described in connection with the manufacture of asphalt cutbacks, although it is to be of the new method is not confined to the production of such materials, which are referred to merely by way of example.

Straight run asphalt produced by the distillation of asphaltic petroleum is too heavy and viscous for most purposes and it has been the practice heretofore to treat the asphalt with a solvent or flux to produce cutbacks which are used in road making, for the production of asphalt paints, as roofing plastics, and for other purposes. The kind and quantity of the solvent or flux used in the production of a cutback depend on the asphalt to be treated and the characteristics of the final product desired,'as for example, in the production of asphalt cutbacks suitable for road making, the asphalt treated may have a melt point of 130 F. and the flux used may be a naphtha distilling between 150 F. and 450 F. This flux may be mixed, for example, with the asphalt in the proportions by volume of 72 to 81 parts of asphalt and 28 to 19 parts of naphtha, and the materials are agitated in an open vessel until a uniform product is produced. In this operation, a substantial amount of the solvent or flux is lost, by evaporation, and as the material lost is made up of the more volatile constituents of the solvent, the solvent is thereby reduced in effectiveness and the length of the operation is prolonged.

The present invention is directed to the provision of a method for producing cutbacks in which loss of the solvent or flux is greatly revduced so that the operations are shortened in time and the cost of the final product is materially reduced. According to the new method, a quantity of finished cutback material is maintained in an intermedite storage chamber from which finished product is continuously delivered to storage and material continuously withdrawn for circulation through a closed conduit which contains impelling and agitating means for maintaining the circulatory flow and effecting a violent agitation of the circulating material. The asphalt to be treated and the solvent are continuously introduced into the conduit through the walls thereof and preferably, the asphalt and solvent are delivered into the conduit at diametrically opposite points and in line with impeller and agitating elements therein.

In carrying out the new method, I prefer to use the apparatus disclosed in my copending application, Serial No.- 693,392, filed October 12, 1933, although various other forms of apparatus may be employed. The apparatus of that application is illustrated in the accompanying drawings, in which Fig. l is a vertical sectional view through the apparatus; and

Fig. 2 is a horizontal sectional view through the tubes of the apparatus containing the agitating and impeller elements.

The apparatus illustrated includes an intermediate storage chamber I having a closed top provided with a discharge outlet 2 and at the bottom of the chamber, there is a discharge opening 3 through which material can flow downward into a hollow body 4, from the opposite sides of which lead two horizontal tubes 5. A shaft 6 carrying sets of impeller blades 1 spaced along it extends through the tubes and the body, each tube there are two sets of blades, these blades being helically formed and so disposed that the blades in each tube operate to force liquid outward through the tube in a direction away from the body. Within each tube between the blades are radial stator vanes 8 which extend inward from the tube walls and terminate close to the shaft. The outer end of each tube is connected to the bottom of the chamber by an upwardly extending conduit 9 and above each inlet opening into the chamber is a plate II] which overlies the opening and causes the liquid entering the chamber to flow helically upward there- The asphalt to be cut back and the solvent are introduced into each disperser tube through diametrically opposed openings I I in the tube walls and these openings lie in line with the first set of impeller blades in the tube, the ends of the blades terminating close to the inner wall of the tube and each set having a dimension lengthwise of the tube which is at least as great as the diameter of the openings II, as illustrated.

During the operation of the apparatus, a circulation of cutback material takes place, the liquid leaving the bottom of the chamber and flowing down into the body. Liquid then flows from the body through each tube, and as the stream of liquid reaches the first set of blades in its tube, the stream is sub-divided into a plurality of smaller streams, each lying between adjacent blades of the set. Heated asphalt in fluid condition fiows continually into the tubeat the periphery of the blades in the form of a stream and as the rapidly moving blades pass across the inlet opening for the asphalt, sections of the asphalt stream are severed therefrom and mingled with the streams of cutback between the blades. The severing of the end sections from the asphalt stream by the mechanical shearing action of the and in '20 high velocity blades causes the asphalt to be broken up into fine particles which are thoroughly distributed through the small streams of cutback by the impact of the blades.

At the other side of the set of blades, the solvent is introduced into the streams of cutback between the blades in the same manner; that is, end sections are severed from a stream of solvent and the 'material in these sections is thoroughly mingled with the cutback between the blades at one side of the set. The solvent thus introduced dilutes the cutback in the streams into which it is delivered, while the asphalt fed into the other side of the tube enriches the cutback in the streams which it enters. As these enriched and diluted streams of cutback are forced out from between the impeller blades, the streams are united under conditions of great turbulence and the whirling liquid is subjected to hydraulic shear and then enters the spaces between the I radial stator vanes, where the motion of the liquid paths, the streams becomes rectilinear. The liquid then passes to the second set of impeller blades where it is violently agitated by the high velocity impact of the blades. After. leaving the second set of blades,

'the liquid is discharged into the conduit which leads it back to the intermediate storage chamher. In the chamber, the streams of liquid from the two disperser -tubes are deflected by the plates and caused to move along upward helical finally mingling so that a more uniform product results.

As previously mentioned, the intermediate storage chamber is provided with a closed top having an outlet opening through which the finished material is continuously'discharged at the same rate that asphalt and solvent to be'treated' are supplied and the use of the closed system in the apparatus prevents evaporationof the solvent. The shaft extending through the tubes and carrying the impeller blades passes out through stuifing boxesat the ends of the tubes and the agitating operations are carried on under pressure resulting fromthe head of liquid in the intermediate storage chamber and the pressure at which the solvent and asphalt are fed. Infiltration of air is, therefore, prevented and no air bubbles can enter the stream being treatedso that the im peller blades operate at high efiiciency. The effectiveness of the blades is also increased by the use of collars or other means on the shaft which, together with the tube walls, confine the stream a being treated so that it has a thin annular form and is acted on only by the outer ends of blades which travel at the highest velocity.

I have found that when the asphalt and solvent are subjected to impact and the shearing action of the high velocity blades at the points where these materials re introduced into the circulating stream of cutback, an excellent dispersion and mixing takes place so that the treatment of the asphalt with the solvent can be completed in a short time.

The production of cutbacks according to the new method can thus be carried on .at a high output rate and without substantial loss of solvent.

- As-compared with prior methods, my new method can be carried out with a saving upto 20% of the solvent, and since the proportion of the solvent saved includes those constituents of the solvent which are of the greatest volatility and effectiveness, the prevention of loss of the solvent not only reduces the cost of materials but also reduces ing a solvent or flux into the cutback stream, and

agitating the augmented stream.

2. A method of making a cutback of a viscous liquid substance which comprises circulating a stream of previously produced cutback, sub-dividing said stream, enriching one subdivision by introduction of said substance, diluting another sub-division by introductionof a solvent or fiux, combining said enriched and diluted sub-divisions, into a single stream, agitating said stream, and continuously, withdrawing a portion of said stream from circulation.

3. A method of making a cutback of a viscous liquid substance which comprises separately introducing saidsubstance and a solvent or flux into separate bodies of previously produced cutback, and thereafter mixing said separate bodies together. I

4. A method of making a cutback of a viscous liquid substance which comprises creating a stream of previously produced cutback, introducing said substance into the stream by cutting end sections 'from a stream of said substance and mingling them with, the cutback stream, introducing a solvent or flux into the cutback stream by cutting end sections from a stream of said solvent or flux and mingling them with the cutback stream, and agitating the augmented cutback stream.

5. A method of making a cutback of a viscous liquid substance which comprises creating a stream of previously produced cutback, introducing said substance into the stream by cutting end sections from a stream' of said substance and mingling them with the cutback stream, introducing a solvent or flux into'the cutback stream by cutting end sections from a stream of said solvent or flux and mingling them with said cutback stream, said substance and said solvent or flux being introduced into said cutback stream at points lying substantially in a plane transverse to the direction of flow of said cutback stream, and agitating said augmented cutback stream beyond said plane.

6. A method of making a cutback of a viscous liquid substance which comprises separately introducing said substance and a solvent or flux into separate bodies of previously produced cutback, agitating said separate bodies, and thereafter, mixing said separate bodies together.

7. A method of making a cutback of a viscous liquid substance which comprises separately introducing said substance and a solvent or flux into separate bodies of previously produced cutback, agitating said separate bodies, andthereafter, mixing said separate bodies together and subjecting the mixture to agitation.

8. A method of making an asphalt cutback which comprises introducing heatedasphalt into a body of previously produced cutback, introducing a solvent or flux into another body of previously produced cutback, and thereafter, mixing said bodies together.

. THOMAS ROBINSON. 

